2. Field of the Invention
This invention relates to stacking of wood such as lumber and plywood for drying or other purposes and more particularly, to retainer arm assemblies provided in an automatic stick laying apparatus for maintaining spacing sticks in position for positioning the spacing sticks on stacked tiers of lumber in selectively spaced relationship to provide proper ventilation between the respective layers or tiers of lumber.
At a very early date it became obvious that lumber must be cured prior to use in order to avoid, or at least minimize, warping due to drying. In the early sawmill days "green" lumber was stacked in "ricks" which defined an inverted "V" configuration, where it was air-dried to reduce the moisture content and provide reasonably straight boards for building purposes. With the development of modern sawmills, the rate of processing and drying or curing of "green" lumber increased to the point that it became impractical and unprofitable to stack lumber in this "rick drying" fashion, and other techniques were devised to accomplish this purpose. The lumber is now stacked for kiln drying or air drying and the stacking is preferably accomplished in multiple rows and layers or tiers by inserting between each tier or layer of boards a number of small spacing sticks which keep the layers spaced and provide ventilating passages through the stack to expose both the upper and lower surfaces of the boards in the stack to the drying air. This procedure serves the purpose of processing a large number of boards of selected size in a relatively short period of time, thereby providing more favorable sawmill economics.